1. Field of the Invention
The present invention relates to an optical microscope that allows an observation of a light emitted by a sample with an illuminating light from a light source irradiating the sample.
2. Description of the Related Art
Conventionally, an optical microscope has been widely used, by which a light emitted by a sample is observed with an illuminating light irradiating the sample. Generally, to obtain a clear image of a sample, i.e., an image on which an objective lens is in focus, it is necessary to keep an objective lens and the sample located at a certain distance therebetween. However, a thermal drift or a variety in thickness of a cover glass covering the sample would cause changes in the distance between the objective lens and the sample, resulting in changes in a focal position and an aberration, thus making it impossible to obtain a clear image. To solve this inconvenience, a mechanical adjustment has been generally employed for corrections of the focal position and aberration. However, since a correction collar for the mechanical adjustment is attached to the objective lens, manipulation of this correction collar is so uneasy that a lot of efforts are necessary, especially when the thickness of the cover glass varies. As a technique to correct the focal position and the aberration without using the mechanical adjustment, an optical microscope using an adaptive optical unit for modulating a wave surface of an incoming light is disclosed (See U.S. Pat. No. 6,771,417, for example).